Earth: Garnet (the gemstone. It's associated with grounding and the earth)Nora (means earth in Czech)Octavia/Ottavia (the number eight, the circles represents the joining of heaven and earth)Olivia (means an olive, and olives and olive trees are very earthy)Primrose (the herb is associated with earth)
Xylina (means made of wood in Greek)

Water:Adriana (might come from the word adur which means water)
Calluna (bot. name for Heather, a plant ruled by water and Venus)Camellia (the tree, associated with water and the moon)Coral
Gwenllian (means flood and sea)Lavinia (means to wash. Comes from the name of a river)LotusMarinaMorwenna (means sea white)
SeamayTallulah (means leaping water)